Solar panels are conventionally formed from an upper layer of glass, an intermediate layer including the solar cell or plurality of solar cells (hereinafter “solar cell”), and a lower layer made of glass or a compound foil. The solar cell is wrapped in an encapsulation material. The encapsulation of the solar cell protects the solar cell from damage and ensures that the upper and lower layers of the solar panel remain adhesively coupled to the solar cell, thereby forming a solar cell “sandwich.” Solar panel manufacturers have conventionally used foil sheets of polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA) as the encapsulation material. The EVA or PVB foil sheets must be carefully positioned around the solar cell and then melted in a laminator and cooled to create the solar panel “sandwich.” This encapsulation process is highly time-consuming for the lamination and the placement of the foil sheets. The encapsulation process also consumes a significant amount of energy to melt the foils.
To address the shortcomings of the traditional foil sheet encapsulation process, solar panel manufacturers have begun to replace the encapsulating foil sheets with a liquid encapsulation material. The liquid encapsulation material is generally formed from a base component and a catalyst component, the combination protecting and adhering to the solar cell. In one exemplary process, the liquid encapsulation material may include a first optically clear material for the front side of the solar cell and a second material including quartz powder for improved conductivity and thermal properties for the rear side of the solar cell. The liquid encapsulation material must be metered and dispensed accurately on the solar cell such that a continuous generally planar layer of liquid encapsulation material is provided over the entire surface area of the solar cell.
Conventional liquid dispenser systems have been largely unsuccessful at providing consistent flow stream quality for the liquid encapsulation material across the width of a solar panel, especially for solar panels of varying size and shape. For example, in liquid dispenser systems with a single elongate dispenser outlet, the accuracy and consistency of the liquid flow across the width of the solar panel changes undesirably as the size of the solar panel changes. In liquid dispenser systems with a plurality of parallel liquid outlets, the variance in flow stream quality across the width of the dispenser may cause separate streams of liquid encapsulation material to flow together and adversely affect the formation of a continuous encapsulation layer on the solar cell. If the dimensions of a solar cell to be encapsulated change from one solar panel to the next solar panel, conventional liquid dispenser systems must be completely reconfigured before dispensing can continue, leading to high amounts of manufacturing downtime.
Additionally, the entire liquid dispenser system must typically be flushed of the liquid encapsulation material between each reconfiguration or every few minutes to avoid setting of the liquid encapsulation material within the dispenser system. However, conventional liquid dispenser systems capture a high amount or volume of encapsulation material between the valves associated with the dispenser and the liquid outlets of the dispenser. This high amount of encapsulation material is completely wasted every time the dispenser system is flushed, and further leads to undesirable dripping of encapsulation material from the liquid outlets between dispensing cycles.
Furthermore, conventional liquid dispenser systems typically meter the flow of each component of the liquid encapsulation material with only gear pumps. For the components of the liquid encapsulation material including abrasive material such as quartz powder, the gear pumps are subject to a high rate of wear and failure. Thus, it would be desirable to provide a liquid dispenser gun and system that address these and other problems with the encapsulation process for a solar panel.